JPH07312206A - High-load fluorescent lamp - Google Patents

Abstract

PURPOSE:To improve maintenance factor by containing specified amounts of La, Y and Gd out of rare earth elements in a strontium borate phosphor. CONSTITUTION:A strontium borate phosphor and minute particle alumina are added to nitrocellulose/butyl acetate solution as binders and substantially suspended and after that the obtained suspension is applied on a glass tube 2 and dried so as to form a phosphor layer 4. Secondarily, it is baked in an electric furnace, an electrode 3 is mounted, ordinary process such as exhaust is executed, mix gas and mercury are sealed, and a base 1 is mounted. At least, one kind of La, Y, and Gd in rare earth elements is contained in the strontium borate phosphor so that deterioration due to attack of mercury ion plasma, which is a major deterioration cause in a florescent lamp, is prevented and maintenance rate can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-pressure mercury vapor discharge lamp that radiates ultraviolet rays, and more specifically, it has a strontium borate phosphor in its fluorescent layer, and the power consumed by positive column discharge is the unit area of the fluorescent layer. The present invention relates to a high load fluorescent lamp having a power consumption of 500 W / m ² or more.

[0002]

2. Description of the Related Art Generally, a fluorescent lamp using a fluorescent substance that emits ultraviolet rays having a near ultraviolet ray of around 350 nm as a main component is called a black light fluorescent lamp, and is used for stage lighting, discrimination of minerals and jewels, or instruments. It is used in a wide range of applications such as lighting. As a phosphor used in this black light fluorescent lamp, a divalent Eu-activated strontium borate phosphor (hereinafter referred to as strontium borate phosphor)
Is known to be excellent in practical use.

As a recent trend, not only fluorescent lamps for general lighting but also fluorescent lamps that emit such ultraviolet rays are becoming more compact and slimmer. There is an active movement to be associated with various uses. This means that the tube wall load of the fluorescent lamp increases and the load applied to the phosphor layer on the inner surface of the glass tube of the fluorescent lamp increases.

The high-load fluorescent lamp in which the power consumed by the positive column discharge is 500 W / m ² or more per unit area of the fluorescent layer has a higher density of excited mercury atoms and mercury ions than the ordinary fluorescent lamp. They become large, and these destroy the crystals on the surface of the phosphor, blacken the phosphor layer, and significantly reduce the lamp output over a long period of time. Even in the strontium borate phosphor, such deterioration factors dominate under high load conditions, and the decrease in ultraviolet radiation over time is remarkable, which greatly hinders the practical application of a near-ultraviolet-excited high-load fluorescent lamp.

In general, a fluorescent lamp is filled with mercury and one or more kinds of rare gases, and ultraviolet rays are generated by discharge, and most of the ultraviolet rays have a wavelength of 254 nm and are only 185 nm.
Although it has ultraviolet rays with a wavelength of nm, in a high load fluorescent lamp, the ratio of the ultraviolet rays with a wavelength of 185 nm is large. It is known that exposing a phosphor to 185 nm radiation generally has a detrimental effect on the emission of the phosphor even in a very short time.

[0006]

Therefore, an object of the present invention is to provide a strontium borate phosphor for a high load fluorescent lamp in which the power consumed by positive column discharge is 500 W / m ² or more per unit area of the fluorescent layer. It is an object of the present invention to provide a high-load fluorescent lamp of near-ultraviolet radiation having an excellent maintenance rate.

[0007]

Means for Solving the Problems As a result of earnest research for the purpose of applying the strontium borate phosphor to a high-load fluorescent lamp, the present inventors have found that among rare earth elements La, Y,
It has been newly found that the retention rate can be improved by incorporating Gd and Gd in a specific amount in a strontium borate phosphor.

That is, according to the high load fluorescent lamp of the present invention, in the high load fluorescent lamp in which the power consumed by the positive column discharge during operation is 500 W / m ² or more per unit area of the fluorescent layer, the fluorescent layer (Sr , Eu) strontium borate phosphor represented by B ₄ O ₇ is contained, and the strontium borate phosphor contains one of rare earth elements La, Y, and Gd, and the content thereof is fluorescent. 10pp for body
It is characterized by being m or more and 5000 ppm or less.

The range of the rare earth element is preferably adjusted to 100 ppm or more and 2000 ppm or less.

As a method of incorporating at least one of La, Y, and Gd of rare earth elements into the strontium borate phosphor, a raw material obtained by mixing necessary components of the strontium borate phosphor before firing (hereinafter referred to as raw raw powder Called)
A method in which a compound containing at least one of La, Y, and Gd of rare earth elements is mixed and fired in a reducing atmosphere at 800 ° C. or higher, or a rare earth compound is mixed with an already fired phosphor to obtain 500 ° C. It can be obtained by any of the methods of re-baking at the above temperature. Oxides are most suitable as compounds of rare earth elements, and nitrates and halides are also effective. Although an organic acid salt such as acetate can be used, it is not suitable if it takes a long time to thermally decompose.

[0011]

As described above, the reason why the strontium borate phosphor containing a rare earth element can be applied to a high-load fluorescent lamp is La, Y, and G.
It can be presumed that the inclusion of at least one of d makes it less likely to deteriorate against the attack of mercury ion plasma, which is the main deterioration factor in the fluorescent lamp.

When the optimum content of at least one of La, Y, and Gd was tested, there was an effect of improvement in the range of 10 ppm or more and 5000 ppm or less. This is because if it is less than 10 ppm, the effect of containing the rare earth element is lost, and if it is more than 5000 ppm, it behaves as a killer and the initial luminous flux is significantly reduced, which is not practical. Further, when the rare earth element is 100 ppm or more, the effect of improving deterioration is large, and when it is 2000 ppm or less, the decrease in the initial output is small.

[0013]

【Example】

[Example 1] 680.0 g of SrO and 110 of B ₂ O ₃
0.0 g, Eu ₂ O ₃ of 17.6 g, and La ₂ O ₃ of 0.
007 g is thoroughly mixed with a ball mill, the raw raw material powder thus obtained is filled in a quartz crucible, and fired at 900 ° C. for 2 hours in a reducing atmosphere. Coarsely crush the obtained baked product with a crusher,
Further, it was pulverized by a wet method, washed, separated and dried, and passed through a 200-mesh sieve to obtain a strontium borate phosphor. The quantitative analysis of La in the strontium borate phosphor thus obtained was 11 ppm.

To the nitrocellulose / butyl acetate solution, 1 wt% of the strontium borate phosphor and fine particle alumina with respect to the phosphor are added as a binder and sufficiently suspended. The obtained suspension was applied to a glass tube 2 having an outer diameter of 20 mmφ and a length of 55 cm shown in FIG. 1 and dried to form a fluorescent layer 4. In this state, the coating amount of the phosphor was 1.5 g. Next, bake in an electric furnace at 580 ° C for 10 minutes,
After mounting the electrode 3, the normal process such as exhausting is performed, and N
Mixed gas of e, Ar, Kr 2Torr and mercury 20m
g was enclosed, the base 1 was attached, and the high-load fluorescent lamp of the present invention was produced.

A tube current of 0.53 is applied to this high load fluorescent lamp.
It was operated under the conditions of A, tube voltage 53.8 V, and tube power 24.0 W. In this state, the tube wall load of the high load fluorescent lamp of the present invention was calculated to be 807 W / m ² .

[Comparative Example 1] A strontium borate phosphor was prepared by the same method as in Example 1 except that La ₂ O ₃ was not mixed, and a high-load fluorescent lamp was manufactured by the same method and operated under the same conditions. A high load fluorescent lamp with a tube wall load of 807 W / m ² was obtained. Initial lighting of this high load fluorescent lamp (0 hours)
Assuming that the lamp output is 100%, the relative value% of the change over time in the lamp output with respect to the lighting time of the high load lamp is examined, and the results are summarized in Table 1.

[0017]

[Table 1]

The lamp output at 0 hours in Example 1 is rather low, which is 99% of that in Comparative Example 1, but it should be noted that the lamp output after 100 hours is 89% in Comparative Example. In contrast, in Example 1, the point is 92%, which is a reverse point. The value of 100 hours in a fluorescent lamp means the first output described in catalogs in the industry, that is,
This means that the initial output of the high-load fluorescent lamp has been improved.

Example 2 A strontium borate phosphor was prepared by the same method as in Example 1 except that 0.68 g of La ₂ O ₃ was mixed. When the La of the obtained phosphor was quantitatively analyzed, it was 985 ppm. A high-load fluorescent lamp was manufactured by the same method, operated under the same conditions, and a tube wall load of 800 W /
A high load fluorescent lamp of m ² was obtained. Comparing the outputs after 100 hours, 89% in Comparative Example 1,
It is extremely high at 94%. Also, the output after 1000 hours is
Compared with 66% in Comparative Example 1, there is a large difference between 81% and 15%, and the maintenance rate is remarkably improved. It should be noted that the 0-hour value tends to decrease due to the inclusion of La, but the improvement in the maintenance rate exceeds that.

[Example 3] A strontium borate phosphor was prepared in the same manner as in Example 1 except that 3.40 g of La ₂ O ₃ was mixed. When the La of the obtained phosphor was quantitatively analyzed, it was 4980 ppm. A high load fluorescent lamp was manufactured by the same method, operated under the same conditions, and a tube wall load of 807W
A high-load fluorescent lamp of / m ² was obtained. The output after 100 hours is as high as 91%, and the output after 1000 hours is 71%, which shows that the maintenance rate is improved.
However, the La content was 1000 pp for both the initial output and the maintenance rate.
It is lower than that of about m.

[Comparative Example 2] A strontium borate phosphor was prepared in the same manner as in Example 1 except that 6.8 g of La ₂ O ₃ was mixed. The quantitative analysis of La of the obtained phosphor was 9690 ppm. A high load fluorescent lamp was manufactured in the same way, operated under the same conditions, and a tube wall load of 807W
A high-load fluorescent lamp of / m ² was obtained.

[0022] [Example 4~9] Y ₂ O _3, respectively, 0.
0074g, 0.74g and 3.7g or Gd
_A strontium borate phosphor was prepared in the same manner as in Example 1 except that 0.0070 g, 0.67 g, and 3.35 g of ₂ O ₃ were mixed. Y of the obtained phosphor,
Or quantitative analysis of Gd shows that Y is 11pp each.
m, 990 ppm, and 5020 ppm, and Gd was 11 ppm, 1030 ppm, and 4900 ppm, respectively. As shown in Table 1, the relative output values of the high-load fluorescent lamps using these phosphors are similar to La when Y and Gd are contained, and are effective in improving the maintenance ratio in a specific concentration range. .

[Comparative Examples 2 to 4] 6.8 g of La ₂ O ₃ and Y
_A strontium borate phosphor was prepared in the same manner as in Example 1 except that 7.4 g of ₂ O ₃ or 6.7 g of Gd ₂ O ₃ was mixed. Quantitative analysis of La, Y, or Gd of the obtained phosphor gives 9690, 10110 pp, respectively.
m, was 9830 ppm. Focusing on Comparative Example 2 in Table 1, the output after 100 hours is 88% and 1000%.
After the lapse of time, 62% and the effect of the inclusion of La are not seen.
This is because if the content of La is too large, it acts as a killer and reduces the initial output and maintenance rate of the high-load lamp. This also applies to Y and Gd.

[0024]

As described above, by improving the strontium borate phosphor in the present invention and applying it to the phosphor layer, the maintenance factor of the high load fluorescent lamp can be greatly improved. As a result, a practical high-load fluorescent lamp that emits near-ultraviolet light can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a high-load fluorescent lamp of the present invention.

[Explanation of symbols]

 1 ... Base 2 ... Glass tube 3 ... Electrode 4 ... Fluorescent layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kayo Hashimoto, 491, Oka, Kaminaka-cho, Anan City, Tokushima Prefecture Nichia Kagaku Kogyo Co., Ltd.

Claims (2)

[Claims] 1. In a high-load fluorescent lamp in which the power consumed by positive column discharge is 500 W / m ² or more per unit area of the fluorescent layer, the fluorescent layer is expressed by (Sr, Eu) B ₄ O _7. The phosphor comprises a strontium acid phosphor, and the strontium borate phosphor contains one of rare earth elements La, Y, and Gd, and the content thereof is 10 ppm or more and 5000 pp relative to the strontium borate phosphor.
A high-load fluorescent lamp characterized by having a length of m or less. 2. The content of the rare earth element is 100 ppm.
The high load fluorescent lamp according to claim 1, wherein the content is 2000 ppm or less.